1917.] NATURAL SCIENCES OF PHILADELPHIA. 207 



MARINE MOLLUSKS OF HAWAII, I-III. 

 BY HENRY A. PILSBRY. 



In the identification of mollusks obtained by the writer in 1913, 

 and those subsequently received from Mr. D. Thaanum, of Hilo, 

 it was found necessary to review all the Hawaiian species of some 

 families. That the studies may be of use to others interested in the 

 Hawaiian fauna, it is proposed to publish the results in a series of 

 articles with illustrations of new forms and those not previously 

 figured. 



It is a pleasure to acknowledge the liberality of Mr. Samuel Hen- 

 shaw, Director of the Museum of Comparative Zoology, who allowed 

 the author to study and "figure specimens from the Pease collection,, 

 contained in that museum. Without these, definite conclusions, 

 would be unattainable in many cases. 



I. THE PHASIANELLID^. 



The Hawaiian Phasianellse are all very small, but of exquisite 

 beauty. Probably all but P. thaanumi belong to the section Tri- 

 coliella Monts., type P. jmlla, if this is separable from Tricolia. 

 For P. thaanumi a new section, Hiloa, may be formed, characterized 

 as in the following: 



Key to Hawaiian Phasianellce. 



a. Peristome projecting forward at junction of columellar and basal 

 margins; shell short, of rapidly enlarging whorls. 



P. thaanumi, n. sp. 

 o^ No projection of the peristome in unbroken specimens. 



b. Axis narrowly, deeply umbilicate; thin P. molokaiensis, n. sp. 



b^. Axis perforate. 



c. Shell ovate, with moderately long spire. 



d. Rather solid; 2.7x2 mm. P. variabilis (Pse.). 



d^. Thin, about 1.8 mm. long P. v. kahoolawensis, n. subsp. 



d. Shell broad, with short spire P. bryani, n. sp. 



Phasianella variabilis (Pease). 



1860. Collonia variabilis Pse., Proc. Zool. Soc. Lond., p. 436. 

 1888. Phasianella variabilis Pse., Pilsbry, Man. of Conch., X, p. 176, 

 PL 39a, figs. 21, 22. 



This species is sometimes common on the beaches east of Honolulu 

 (which may be taken as type locality), and I have taken it at Haleiwa, 



